1. Field of the Invention
The present invention relates to a silver halide photosensitive material for color-photography and an image formation method using the same. Specifically, the present invention relates to a silver halide photosensitive material for color-photography, which is suitably used in a cost reductive laser luminous source and an image formation method using the same, and in particular, to a silver halide photosensitive material for color-photography capable of attaining stable characteristics when scan exposure is performed using a cost reductive laser luminous source and image processing is performed after a short latent image period.
2. Description of the Related Art
Recently, impact of digitization has been remarkable in the field of color-printing using color-printing paper. For instance, a digital exposure system using a laser scan exposure shows the elongation of a fast diffusion rate as compared with a conventional analog exposure system which directly prints images by a color printer using a processed negative color film. Such a digital exposure method has a characteristic of providing a high image quality by processing an image, and thus it plays a very important role in improvement of color-print qualities using color-printing paper. In addition, since a high image-quality color print can be easily obtained from these electrographic recording medium, the use of digital cameras is rapidly spreading, thus the digital exposure system is expected to become more popular.
On the other hand, as a color print method, techniques such as an ink jet method, a sublimated type method, and color xerography have each progressed and are recognized for their ability of providing good photographic image qualities. Among these techniques, the characteristics of the digital exposure method using color-printing paper include a high image quality, a high throughput, and a high solidity of an image. It is desired to further develop these characteristics and to provide high image quality photographs more easily and with lower cost. If so-called one stop service of a color print becomes possible (i.e., one shop receives a recording medium of a digital camera from a customer and finishes processing to return a high image-quality print to the customer in a short time such as a few minutes), the predominance of the color print using color-printing paper will further increase. If a rapid processivity of color-printing paper is raised, a printing apparatus, which is smaller in size and lower in costs while having high productivity, can be used, and thus the one-stop service of a color print is expected to further spread. From these points, in particular, it is important to raise the rapid processivity of color-printing paper.
In order to make the one-stop service of the color print using color-printing paper possible, analyses from various viewpoints such as shortening of exposure time, shortening of the so-called latent image time from the exposure to the initiation of the processing, and shortening of time period from the processing to the drying are required. Thus, conventionally, various kinds of proposals have been proposed based on such viewpoints.
The time required for exposing one sheet of prints is dramatically shorter compared with other processes, thus there is no substantial problem in uses of printers generally used in shops. The latent image time has been designed to be shortened as much as possible. Shortening the time from processing to drying has been also performed. Furthermore, there are several proposals for performing the process rapidly by appropriately designing a processing liquid composition, a processing temperature, conditions for stirring a processing liquid, cover printing of photosensitive material, drying method, and so on.
On the other hand, forming a digital image in color-printing paper by laser scan exposure is performed. Conventionally, in order to provide a blue laser, a SHG component has been used in order to convert a laser beam emitted from a gas laser or a semiconductor laser having a longer oscillation wave length than gas lasers into a laser having a shorter wavelength. In the case of using the gas laser, the sizes of an exposure device should be enlarged, while the semiconductor laser may be miniaturized to some extent. However, in the case of using the semiconductor laser, there are limits to cost reductive and miniaturization of a printer.
Recently, a blue semiconductor laser (announced by Nichia Corporation on the 48th Spring Meeting of the Japan Society of Applied Physics and Related Societies, March, 2001) with a wave length of 430 to 460 nm which does not use an SHG component has been developed, thus the possibility to provide a more inexpensive printer is increasing.
For the above-mentioned purpose, we conducted a scan exposure on color-printing paper with a blue semiconductor laser and performed analyses under conditions of a short latent image time of less than 9 seconds and a color development in a short time of less than 28 seconds. However, the obtained prints did not provide stability in color. Even when we repeatedly printed one image, every print obtained differed in color.
We conducted various analyses in order to solve the above problem, and we finally found out that preparing a silver halide emulsion used for color-printing paper with adding a specific metal complex therein is effective.
As a silver halide emulsion used for color-printing paper, a silver halide emulsion with high silver chloride content is used to meet requirements of the rapid processing. Attempts to include various kinds of metal complexes into a silver halide emulsion with high silver chloride content have been disclosed. In order to improve failure in high exposure and to obtain a hard tone wedge at high exposure intensity, doping of Ir complex has been well known in the art. For instance, Japanese Patent Application Publication (JP-B) No. 7-34103 discloses that a localized phase having higher silver chloride content is provided and an Ir complex is doped in such a phase to solve the problem of latent image sensitization. U.S. Pat. No. 4,933,272, discloses that low exposure failure can be reduced by including a metal complex which contains NO or NS in a ligand. U.S. Pat. Nos. 5,360,712, 5,457,021, and 5,462,849 disclose that reciprocity failure can be reduced by including a metal complex which contains a specific organic ligand in a ligand. U.S. Pat. Nos. 5,372,926, 5,255,630, 5,255,451, 5,597,686, 5,480,771, 5,474,888, 5,500,335, 5,783,373, and 5,783,378 discloses that performances, such as reciprocity law characteristics of a high silver chloride emulsion, are improvable in combinations of the metal complex, which contains Ir complex and NO in a ligand. Japanese Patent Application Laid-Open (JP-A) Nos. 2000-250156, 2001-92066, and 2002-31866 disclose the emulsion technique, which is excellent in the latent image stability after exposure with uses of combinations of Ir complex and Rh complex or the like.
Furthermore, JP-A Nos. 58-95736, 58-108533, 60-222844, 60-222845, 62-253143, 62-253144, 62-253166, 62-254139, 63-46440, 63-46441, and 63-89840, and U.S. Pat. Nos. 4,820,624, 4,865,962, 5,399,475, and 5,284,743 disclose that high sensitivity can be obtained by making a localized phase having a higher content of silver bromide with various forms in an emulsion with high silver chloride content.
U.S. Pat. Nos. 5,726,005 and 5,736,310 disclose that the emulsion containing I having a maximum concentration in the sub surface of a high silver chloride emulsion allows a high-sensitivity emulsion with little high luminance failure to be obtained. In the example in European Patent (EP) No. 928,988A, it is indicated that the emulsion excellent in reciprocity failure, temperature dependency and pressure property at the time of exposure is obtained by including a specific compound in particles that form I band at the time of 93% particle formation.
However, the prior art neither discloses nor teaches about instabilities of photographic characteristics and improvements thereof at the time of performing a scan exposure on color-printing paper by a blue laser, and carrying out the color development processing with a short latent image period of 9 or less seconds.